Fuse



April 13, 1937- T. BIRKENMAlER 2,077,207

FUSE

Filed Feb. 28, 1956 Patented Apr. 13, 1937 FUSE Theodore Birkenmaier, St. Louis, Mo., assignor to W. N. Matthews Corporation, St. Louis, Mo.. a corporation of Missouri Application February 28. 1930, Serial No. 66,179

33 Claims.

This invention relates to fuses, and with regard to certain more specific features, to expulsion fuses.

Among the several objects of the invention may be noted the provision of an expulsion fuse in which the fuse link, after blowing, and after being expelled from the fuse tube shall not be electrified (alive) in the condition that it hangs from the fuse unit; the provision of apparatus of this class in which mechanism that accomplishes the de-electriiication of the link shall also be useful in effecting a wide separation of the link at the point oi' fusion; and the provision of a device of the class described which may be easily re-fused. Other objects will be in part obvious and in part pointed out hereinafter.

The invention accordingly comprises the eiements and combinations of elements, features of construction, and arrangements of parts which 0 will be exempliiied in the structures hereinafter described, and the scope of the application of which will be indicated in the following claims.

In the accompanying drawing, in which is illustrated one of various possible embodiments of the invention,

Fig. 1 is a vertical section taken through a fuse box, showing in elevation therein a fuse tube, the parts being in normal fused and unblown condition;

Fig. 2 is a view similar to Fig. l showing a blown condition of the fuse;

Fig. 3 is a vertical section on line 3--3 of Fig. 1:

Fig. 4 is a horizontal section on line 4 4 of 3;, Fig. 1; and,

Fig. 5 is a horizontal section, taken on line 5 3 of Fig. 1.

Similar reference characters indicate corresponding parts throughout the several views of the drawing.

It has been heretofore known to provide a fusecontaining tube having an upper contact and a lower contact spaced from the open bottom of the tube. Between the contacts was connected a fuse link with a fusible element near the upper contact. This link passed through the tubular portion. Upon melting out of the link at said fusible section. the engendered gases, or even auxiliary mechanical means, in some cases, caused the fuse link to be projected from the tube. The circuit was thus broken, but the hanging fuse link was still connected to a contact in the circuit. so that it was either alive or electrified.

'I'hus there was always the danger that a line- 55 man or another might contact it and become grounded in the circuit, or that the dangling link would contact other conducting objects and so cause trouble. The present invention overcomes this difficulty without the necessity of releasing the link upon blowing.

Referring now more particularly to Fig. i, there is shown at numeral I a fuse box which carries a pivot pin 3 for the hook-shaped portion l of a door l, the latter carrying an eye 9 for manipulating the same to open and closed positions. It is to be understood that in open position, the door may be entirely separated from the box by unhooking the eye from the pivot pin 3, but that in closed position, the pin 3 and eye are inseparable. It is to be understood that both the box l and door I are composed of insulating material, such as porcelain and bakellte, respectively.

At its upper end the door 'i is provided with a support Il to which is rigidly fastened an upper terminal-engaging element I3 in which is threaded an insulating, hollow, fuse tube I5. The hollow portion of the tube I5 is in alignment with an opening I1 in the terminal-engaging element I3. The terminal-engaging element has threaded therein a cap I3 whereby the upper conducting element 2| of a fuse link may be held in said opening I'I.

The terminal-engaging element gudgeons 23 which cooperate with notches 24 in spring holding clips 25. The spring clips 26 are fastened to a conducting block 21 to which is fastened a line wire 29. One gudgeon 23 is located on each side of the terminal-engaging element i3 to accommodate respectively one spring clip 23. Between the pair of spring clips 23 is a centrally located clip 3| which, when the gudgeons 23 are seated in the notches 2l of the clip 25, seats on the upper fiat surface of the closure cap I3. By this means, when the door 'l is angled to a closed position, the terminal-engaging element I3 is springingly held in the spring clips 25 and 3|. The door is thus held shut and contact made for the terminal-engaging element I3.

From the above it will be understood that the element I3 and insulating tube I5 are rigidly held on the door 1. The tube I5 extends downwardly. and, at its lower end is open as indicated at numeral 39. The lower end is adjacent the lower open portion 4I of the box I. Concentrically, and slidably arranged upon the lower portions of the insulating tube I5 is a second insulating tube 43. The tube 43 is sldable from the position shown in Fig. l to that shown in Fig. 2. It has a lower open end 45 adjacent said lower open end 33 of the tube II.

I 3 carries Rigidly fastened about the lower end or the slidabie insulating tube I3 is a contact I1 which carries a clamp I3 for the lower endof the fuse link 5I.

Surrounding the slidable insulating tube I3 is a second but movable terminal engaging element 53. This second element 53 instead of being fastened to the tube I3, as is the element I1. is relatively slidable thereon and also is slidably mounted on the door 1. The slidable mounting on the door 1 is accomplished by means of a slide member 55 slldable in a guide 51 on said door 1. A cover plate 53 holds and prevents the slide 55 from coming out of the guide 51. I t will be apparent from the drawing that the slide 55 is fastened rigidly to the member 53, a space 5I being left therebetween for permitting the element 53 to slide up and down. The motion of the terminal-engaging element 53 is limited by the contact of opposite ends of the metal around space 5I with the holding plate 53.

The element 53 also carries oppositely disposed gudgeons 53 which cooperate with spring clips 35`attached to a lower line terminal 51. A line wire I3 completes the circuit.

In order to prevent the insulating telescoping tube I3 from turning with respect to the terminaiengaging element 53 in which it slides, a pin 1I in the element 53 cooperates slidably with a groove 13 in the tube I3. Contact between the upper end of the groove 13 and the pin 1I also limits the downward movement of the tube I3 with respect to the terminal-engaging element 53. The downward movement of the tube I3 is greater than that of the element 53.

The fuse link 5I has the upper conducting element 2I, a fusible element 15 therebelow but near the upper terminal-engaging element I3, and a lower conducting element 11 which passes downwardly and out of the open ends 33 and I3 of the tubes I5 and I3. where the link is given a hairpin turn and led upwardly to be fastened at the clamp I3.

Below the terminal-engaging element I3, the box I is provided with one element 35 of a septum, the other elements 31 of which is carried by the door 1. These elements 35 and 31. together, form a complete septum which prevents arcing between the upper terminal-engaging element I3 and the lower terminal-engaging element 53.

The operation of the device is as follows:

Assuming-the door 1 to have lbeen opened and removed from the box I, the cap I3 is unscrewed from the upper, xed, terminal-m8581118 element I3. The fuse link is then fed through the opening I1, until a head portion on the upper conducting portion 2I is adapted to be clamped by applying the screw I3. 'Ihe lower conducting element 11 then is extending out of the lower ends of the tubes I5 and I3. while the fusible section 15 is far up in the tube I5.

Next, the tube I3 is pushed up from the position shown in Fig. 2 into the position shown in Fig. l. In doing this, the terminal-engaging element 53 is contacted by the contact I1 and pushed to its Fig. 1 position on the door. The lower, conducting portion 11 of the link 5I is then given a hairpin turn and led up to the clamp I9 where it is fastened. Then, upon applying the eye 5 of the door 1 to the pin 3, and rotating the door shut, the parts will be positioned as shown in Fig'. l. It is to be understood that after the link is fastened at 2 I', the mere threading of it through the clamp I3 and drawing it tight, will bring toaovmov gether the contact I1 and element 53 by sliding the tube I3 in on the tube I5.

The gudgeons 23 and clamp plug IS are springingly held in the spring'clips 25 and 3i respectively, and the gudgeons B3 are springingly pressed down by the spring clips 55. It will be understood that inasmuch as the clips 25, 3| and 55 are conducting, that current is then available to pass through the fuse link. The downward tensioning eiect of the upper clips 25, 3i serve to hold the door l snugly. The downward tension oi' the lower clips 65 on the gudgeons 53 causes a tendency to move down the slidable conducting elements 53 against the conducting elements I1. The conducting element I1, being fastened to the slidable insulating tube I3 cannot move downwardly. because the tube I3 rests by gravity on the hairpin turn oi' the fuse link. Hence, not only does the contact between the spring 55 and gudgeon 63 result in a good currentcarrying contact between members 53 and I1, but it also causes the fuse link to be ptit under some tension. This tension is augmented by the gravity effect of the combined weights oi' the members I3, I1 and 53.

Upon an overload, the fusible section 15 fuses. 'Ihis may be accompanied by a violent. expansion of gas, as upon a heavy overload. or not, as in the case of a dragging overload. In either event, the

slidable terminal-engaging element 53 will be forced downwardly, ilrst by the combined action of gravity and the spring clip 55, and iinally by gravity only, from the position shown in Fig. l to that'shown in Fig. 2. Ihefdescent is by reason oi' the fact that the supporting action of the fuse link no longer is present under the tube I3. Consequently, the tube I3 can descend from the Fig. 1 position to that shown in Fig. 2 and this takes away the support oi the member I1 from the member 53. The descent of the member 53 is limited4 and arrested by contact oi the upper end o! the slot 5I with the plate 53 (Fig. 2); whereas. the descent of the tube I3 continues but is ultimately limited by contact between the upper end of the groove 13 with the pin 1I. A ilxed septum 1I at the bottom of box I prevents ionized gases from nnding ready access back into the box.

The effect of the above action is several-fold. In the first place, the fuse` link is suitably tensioned in the circuit Vby the springs 55, so that upon melting of the fusible element 15, there is an immediate tendency to separate the adjacent conducting elements 2i and 11. However, the sprin's 25 and 3| add no tension on the fuse link. The force of these springs is carried by the pin 3 of the door hinge. 'This is advantageous because by this means enough but not too much tension is obtained. The sliding action under springs 55 is easy, whereas that4 under springs 25 and 3| must be more harsh in order to hold shut the door. This harsh action might break the link ii' applied thereto.

In the second place. the telescopic elongation of the eil'ective fuse tube, by reason of the dropping of tube I3, causes a quick withdrawal of the conducting element 11 from the fuse cartridge, as indicated in Fig. 2. Otherwise stated, the descent of the tube I3 eiects drawing out of the link.

In the third place, the fuse link 5I fastens to the element I'I only and when this element I1 electrically disconnects from the .element 53,

there is no longer any electrical connection be.

tween the fuse link and the line wire 59. Thus the descending link is electrically dead and harmless, both to the operator and in respect to surrounding objects. Heretofore, the depending link has been undesirably electrically alive. This is true whether or not the clips 65 do not follow the gudgeons B3 for the whole stroke of the gudgeons or whether they do as in Fig. 2.

It will also be seen from Fig. 2 that the projecting end of the tubular element 43 forms a sure, visible indicator of the blown condition of the fuse.

From the position of Fig. 2, the door 1 may be removed from the box I and the device re-fused as above described.

In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results attained.

As many changes could be made in carnlg utf the above constructions without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.

I claim:

l. In apparatus of the class described, two groups of line terminals, a terminal-engaging element for one group of line terminals, a terminalengaging element for the other group of line terminals, an extension from the ilrst terminal-engaging element, said second terminal-engaging element being movable with respect to the extension, a contact movable with respect to the second terminal-engaging element and separable therefrom, and a fuse link ioining the rstnamed terminalengaging element with the contact and adapted normally to hold together the second terminal-engaging element and the contact.

2. In apparatus of the class described, spaced line terminals, a fuse support, a terminal-engaging element on said support and cooperating with one line terminal, another terminal-engaging element movable on the support and a contact movable with respect thereto, a fuse fastening means on the contact, a fuse link passing from the first engaging element through said second engaging element and through and to the contact, the second engaging element and contact being movable and held in engagement by the unfused link and being separable when the link fuses.

3. In apparatus of the class described, spaced line terminals. a fuse support, a terminal-'engaging element on said support and cooperating with one line terminal, another terminal-engaging element movable on the support and a contact movable with respect thereto, a fuse fastening means on the contact, a fuse link passing from the iirst engaging element through said second engaging element and through and to the contact, the second engaging element and contact being movable and held in engagement by the unfused link and being separable when the link fuses, the line terminal which engages the second engaging element being adapted to force said element against the contact to tension the link.

4. A fuse comprising a fuse tube, a terminal element at one end of said tube, said tube being open at the other end, a second slidable tube on said first tube, said second tube having an open end normally adjacent the open end of the first tube, a fuse contact on said slidable tube, a fuse Joining said last-named contact and said terminal element, and a second terminal element slidable on said slidable tube adapted to be engaged by said contact when the link is in connected position.

5. In a fuse, a xed fuse tube, a terminal element at one end of said tube, said tube being open at the other end, a second slidable tube on said first tube adjacent the open end, said second tube having an open end normally adjacent the open end of the rst tube. a second terminal element slidable with respect to said siidable tube. a contact on the slidable tube lying outside the two terminal elements. and a fuse adapted to be fastened by the terminal element and to extend through the xed tube and to hold the slidable tube to force the contact against the second terminal element and to bias the latter toward the first terminal element.

6. In a fuse, a xed fuse tube, a terminal element at one end of said tube, said tube being open at the other end, a second slidable tube on said first tube adjacent the open end. saidsecond tube having an open end normally adjacent the open end of the rst tube, a second terminal element slidable with respect to said slidable tube, a contact on the slidable tube lying outside the two terminal elements, and a fuse adapted to be fastened by the mst-named terminal element and to extend through the fixed tube and to hold the slidable tube to force the contact against the second terminal element to bias the latter toward the first terminal element and means for tensioning the second terminal element against said contact.

'7. In apparatus of the class described, a box, a door on said box, upper and lower line terminals in said box, a terminal-engaging element on said door for contactingl said upper line terminal, an insulating tube extending from said upper terminal-engaging element downwardly past the lower line terminal, a second insulated tube telescoping the first tube, a contact on said second tube adapted to fasten a fuse link. a link joining said last-named contact and the terminal-engaging element. and a terminal-engaging element movable on said door and adapted to be engaged by said contact when the contact is moved toward the upper terminal-engaging element.

8. In apparatus of the class described, a box, a door on said box, upper and lower line terminals in said box. a terminal-engaging element on said door for said upper line terminal, an insulating tube extending from said upper termina'l-engaging element downwardly past the lower line terminal, a second insulated tube telescoping the first tube, a contact on said second tube adapted to fasten a fuse link, a link Joining said last-named contact and the terminal-engaging element, and a terminal-engaging element movable on said door and adapted to be engaged by said contact when the contact is moved toward the upper terminal-engaging element, said link in normal position holding said. contact and lower terminal element toward the upper terminal element.

9. In apparatus of the class described, a box, a door on said box, upper and lower line terminals in said box, a terminal-engaging element on said door for said upper line terminals, an insulating tube extending from said upper terminal-engaging element downwardly past the lower line terminal, a second insulating tube teiescoping the first tube, a contact on said second tube adapted to fasten a iuse link, a link joining said last-named contact and the terminal-engaging element, and a terminal-engaging element movable on said door and adapted to be engaged by said contact when the contact is moved toward the upper terminal-engaging element. said link in normal position holding said contact and lower terminal element biased toward the upper terminal element, said lower line terminal resiliently biasing the lower terminal element away from the upper terminal element when said terminal elements contact their respective line terminals.

l0. In apparatus oi' the class described. a box, a door on said box, upper and lower line terminais in said box, a terminal-engaging element on said door for said upper line terminals, an insulating tube extending from said upper terminal-engaging element downwardly past the lower line terminal. a second insulated tube telescoping the first tube, a contact on said `second tube adapted to fasten a fuse link, a link Joining said last-named contact and the mst-named terminal-engaging element. and a terminal-engaging element movable on said door andadapted to be engaged by said contact when the contact is moved toward the upper terminal-engaging element, said lower terminal-engaging element being thereby moved to such a position that when it engages the lower line terminals, said lower line terminals are tensioned to force the lower terminal-engaging element against said contact to effect electrical engagement with and tensioning oi' said link.

11. In apparatus ol the class described, a boxl a door on said box, upper and lower line terminals in said box, a terminal-engaging element on said door for said upper line terminals, an insulating tube extending from said upper terminal-engaging element downwardly past the lower line contacts, a second insulated tube telescoping the nrst tube, a contact on said second tube adapted to fasten a fuse link, a link joining said last-named contact and the first-named terminal-engaging element, and a'. terminal-engaging element movable on said door and adapted to be engaged by said contact when the contact is moved toward the upper terminal-engaging element, said lower terminal-engaging element being thereby moved to such a position that when it engages the lower line terminals, said lower line terminals are tensioned to force the lower terminal-engaging element against said contact to effect electrical engagement and tensioning oi' said link, the movement of the lower terminal-engaging element with respect to the door being limited to be less than the movement of the second tube and contact with respect to the lower terminal-engaging element.

l2. In apparatus of the class described, spaced, resilient line terminals, arelatively xed terminal-engaging element contacting one line terminal. a relatively movable terminal-engaging element contacting the other line terminal, an extension from the relatively ilxed terminal-engaging element supporting the movable terminaiengaging element for limited movement, a movable fuse contact supported for movement into and out oi' electrical engagement with the movable terminal-engaging element, and a link Joining the iixed terminal-engaging element and said movable contact which in normal position forces said contact against the movable terminal-engaging element to move the latter to resiliently engage the resilient line terminal.

i3. In apparatus of the class described, line terminals,` at least one of which is resilient, a fuse comprising a rigid support, a relatively xed terminal-engaging element for one set o! line terminals, a relatively rigid insulating tube extending from slid iixed terminal-engaging element. a movable terminalwam element having limited motion on said support and surrounding said tube, an insulating tube slidable on said `rigid tube and between it and the movable terminal-engageable element, and a fuse contact on said slidable tube adapted to engage said movable terminal-engaging element to torce the same to assume a springing contact with the resilient line terminal. means tor `fastening a fuse link to said contact and to the fixed terminal-engaging element. said contact when the fuse link separates being movable with and away from said movable terminal-engaging element.

14. In apparatus or the class described, a box, springing line terminals in said box. a door on said box, a relatively ilxed terminal-engaging element attached to said door engageable with one set of line terminals, a relatively movable terminal-engaging element on said door movable to a position o1 springing engagement with the other set of line terminals, a tubular insulating member movable with respect to said movable terminal-engaging element to a greater degree than said movable terminal-engaging element moves on the door, a contact on said tube. a fixed tube extending from said iixed terminal-engaging element and into said slidable tube and through said movable terminal-engaging element, and a fuse joining said contact and said ilxed terminal-engaging element adapted in connecting position to force the contact against the` movable terminal-engaging element whereby the tension of the line terminal tensions said link through force applied by the line terminal to the -v movable terminal-engaging element and the contact, said contact being movable away from the movable terminal-engaging element when the link separates.

15. A fuse comprising an insulating tube, a iixed terminal-engaging element enclosing one end of said tube, a movable terminal-engaging element at the other end of the tube, a telescoping and insulating tube associated with the fixed insulating tube, and a contact on said telescoping tube engageable with said movable terminal-engaging element.

i6. A fuse comprising an insulating tube, a fixed terminal-engaging element enclosing one end of said tube, a movable terminal-engaging element at the other end o! the tube, a telescoping and insulating tube associated with the iixed insulating tube, a contact on said telescoping tube engageable with said movable terminal-engaging element. both oi said tubes having normally adjacent open ends, and a i'use link electrically'ioining .the iixed terminal-engaging element with said contact.

i7. A fuse comprising an insulating tube. a fixed terminal-engaging element enclosing one end of said tube, a movable terminal-engaging element at the other end of the tube, a telescoping and insulating tube associated with 'the fixed insulating tube, a contact on said telescoping tube engageable with said movable terminalenssing element, both oi' said tubes having normally adjacent open ends. and a fuse link electrically ioining the ilxed terminal-engaging element with said contact and normally passing through both tubes and about their open ends.

i8. A fuse comprising an insulating tube, a llxed terminal-engaging element enclosing one end ol said tube, a movable terminal-engaging element at the other end of the tube, a telescoping and insulating tube associated with the fixed insulating tube, a contact on said telescoping tube engageable with said movable terminalengaging element, both oi said tubes having normally adjacent open ends, a fuse link electrically joining the xed terminal-engaging element with said contact, and a support comprising means fixedly attached to the fixed terminal-engaging element and to which said movable terminalengaging element is slidably attached.

19. A fuse comprising a tube, a relatively fixed terminal-engaging element thereon, a relatively movable terminal-engaging element thereon, a telescoping member, a contact on said telescoping member, a link joining said xed terminalengaging element and said contact and adapted to hold the telescoping member in such a position that the contact and the movable terminal-engaging element are normally in electrical contact, said contact and movable terminal-engaging element being separated by the sliding action oi said movable terminal-engaging element upon parting of the link.

20. A fuse comprising a tube, a relatively fixed terminal-engaging element thereon, a relatively movable terminal-engaging element thereon, a telescoping member, a contact on said telescoping member, a link joining said xed terminalengaging element and said contact and adapted to hold the telescoping member in such a position that the contact and the movable terminal-engaging element are normally in electrical contact, said contact and movable terminal-engaging element being separated by the sliding action of said movable terminal-engaging element upon breaking of the link, said link in unbroken condition normally supporting said telescoping member but in broken condition releasing the same to withdraw a substantial portion of the link from the tube. 4

2l. A fus'e comprising a tube, a relatively fixed terminal-engaging element thereon, a relatively movable terminal-engaging element thereon, a telescoping member, a contact on said telescoping member, a link joining said iixed terminalengaging element and said contact and passing through the tube and adapted to hold the telescoping member in such a position that the contact andthe movable terminal-engaging element are normally in electrical contact and biased toward the xed element, said contact and movable terminal-engaging element being separated by the sliding action of said movable terminalengaging element upon the parting of the link.

22. Afuse comprising a rigid member, a relatively xedtermgial-engaging element thereon, a relatively movable terminal-engaging element thereon, aslidable member on the rigid member, a contact on said slidable member, a link joining said iixed terminal-engaging element and said contact and adapted to hold the slidable member in such a position that the contact and the movable terminal-engaging element are normally in electrical contact, said contact and movable terminal-engaging element being separated by the sliding action of said slidable member upon the parting of the link.

23. A fuse comprising a rigid member, a relatively xed terminal-engaging element thereon, a relatively movable terminal-engaging element thereon, a slidable member on the rigid member, a contact on said slidable member, a link joining said nxed terminal-engaging element and said contact and adapted to hold the slidable member in such a position that the contact and 75 the movable terminal-engaging element are normally in electrical contact, said contact and movable terminal-engaging element being separated by the sliding action of said slidable member upon the parting of the link and said slidable member withdrawing the link from said xed engaging element.

24. In apparatus of the class described, an enclosing box having an open lower end, upper and lower springing line terminals in said box, a door on the box, a relatively fixed terminalengaging element attached to said door engageabie with the upper set of line terminals, a lower relatively movable terminal-engaging element on said door movable to a position of springing engagement with the lower set of line terminals, a tubular insulating member downwardly movable with respect to said movable terminal-engaging element to a greater degree than the downward movement of said movable terminal-engaging element on the door, a contact on said tube, a fixed tube extending from the.xed terminalengaging element and surrounded by said slidable tube and extending through said movable terminal-engaging element, and a fuse joining said contact and said xed terminal-engaging element adapted in connected position to bias the contact and the movable terminal-engaging element toward the ilxed terminal-engaging element, whereby upon closure of the door the lower line terminal is tensioned to react to tension the link and improve the electrical contact between the contact and lower terminal-engaging element.

25. In apparatus of the class described, an enclosing box having an open lower end, upper and lower springing line terminals in said box, a door on the box, a relatively fixed terminal-engaging element attachedto said door engageable with the upper set of line terminals, a lower relatively movable terminal-engaging element on said door movable to a position of springing ensagement with the lower set oi line terminals, a tubular insulating member downwardly movable with respect to said movable terminal-engaging element to a greater degree than the downward movement of said movable terminal-engaging element on the door, a contact on said tube, a

fixed tube extending from the fixed terminal-engaging element and surrounded by said slidable tube. and extending through said movable terminal-engaging element. and a fuse joining said contact and said i'lxed terminal-engaging element adapted in connected position to bias the contact and the movable terminal-engaging element toward the xed terminal-engaging element whereby upon closure of the door the lower line terminal is tensioned to react to tension the link and improve the electrical contact between the contact and lower terminal-engaging element and whereby upon separation of the link the contact falls away from the lower terminal-engaging element said movable tube telescoping out from the fixed tube to withdraw the remainder of the link therefrom and give visible indication that the fuse link has parted.

26. In apparatus o! the class described, line terminals, a. terminal-engaging element permanently engageable with one line terminal without movement after manual engagement and until manual disengagement, a terminal-engaging means for the other line terminal, an extension from the terminal-engaging element, said terminal-engaging means being movable with respect to the extension, and a fuse link joining said terminal-engaging element and the terminal-engaging means adapted normally to hold said terminal-engaging means in a position against its respective line terminal, but when fused. to permit movement of said terminal-engaging means i away from said respective line terminal to draw the link away from said terminal-enzimi!!! element without movement oi said terminal-engaging element.

27. In apparatus of the class described, line terminals. a terminal-engaging element permanently engageable with one line'terminal without movement after manual engagement and until manual disengagement, terminal-engaging means for the other line terminal, said terminal-engaging means having at least one part movable to electrically disconnect from the respective line terminal. and a fuse joining said part with the other terminal-engaging element. said fuse when connected and unfused normally holding said terminal-engaging means in electrical connection with its respective terminal-engaging element but when fused to electrically separate these without movement of said terminal-engaging element.

line terminals in the box. a terminal-engaging element permanently engageable with one line terminal, terminal-engaging means for the other line terminal without movement after manual engagement and until manual disengagement. a fuse tube extending from the terminal-engaging element. the terminal-engaging means having at least one part movable with respect to said tube away from the said terminal-engaging element. a fuse link connecting said movable part and said terminal-engaging element adapted normally to bias the terminal-engaging means toward the terminal-engaging element, and when fused to permit the terminal-engaging means to move from the terminal-engaging element to draw said link from said tube without movement of said terminal-engaging element, and a manually operable door hinged to the box and carrying said terminal-engaging clement to eilect said 45 manual operation thereof.

29. In apparatus of the class described, a box. spaced line terminals therein. one ci' which terminals has abias. a door hinged to the box, a fuse tube on the iioor, terminal-engaging elements on 50 said tube cooperable with said line terminals, at

least one of said terminal-engaging elements be ing movable with respect to the tube, and a fuse link joining with said movable terminal-engaging element. means for rigidly holding said link at 55 its other end to bias said movable terminal-en swing element against the line terminal having the bias. whereby upon blowing of the link, said movable terminal-engaging element is biased to draw the link from the tube without movement of oo said door.

30. In apparatus of the class described, a base. spaced line terminals thereon. one of said termizs, In apparatus of che class described, n. im,

nais having a bias away from the other, a hinged member on the base, terminal-engaging elements terminal-engaging element, means for rigidly holding said link at its other end to the other terminal-engaging element to bias said movable terminal-engaging element against the biased line terminal in a predetermined position oi' the hinged member, whereby upon blowing of the link said movable terminal-engaging element is biased by the biased line terminal to draw the link without movement of said hinged member from said predetermined position.

3l. In apparatus of the class described, a base. spaced line terminals thereon, a hinged member on the base, terminal-engaging elements on the hinged member cooperable with said line terminals, at least one of said terminal-engaging elements being movable with respect to the hinged member, a fuse link Joining with said movable terminal-engaging element. means for rigidly holding said link at its other end to the other terminal-engaging element to bias said movable terminal-engaging element into contact against the other line terminal, said contact being resilient. whereby upon blowing of the link said movable terminal-engaging element is movable from its line terminal to draw the link without movement of said hinged member.

32. In apparatus of the class described. a base. at least one line terminal thereon, a hinged member on the base. at least one terminal-engaging element on the hinged member which is movable and cooperable with said line terminal. a fuse link joining said movable terminal-engaging element. means for holding said link at its other end to hold said movable terminal-engaging element against said line terminal in a predetermined position of the hinged member.. and means whereby upn blowing of the link said movable terminal-engaging element is released without movement of said hinged member from said predetermined position.

33. In apparatus of the class described, a box, a hinged door on the box movable into closed position, at least one line terminal in the box, at leasty one terminal-engaging element relatively movable on and movable with the door and cooperable with said line terminal when the door is closed. a fuse link joining said terminal-engaging element, means for anchoring said link in its other end with respect to the door to force said movable engaging element against said line terminal when the door is closed. and means whereby upon blowing of the link said movable terlumai-engaging element is released without movement of said door from closed position.

THEODORE B.

CERTIFICATE 0F CORRECTION.

Patent No. 2,077,207. April 15, 1937.

THEODORE BIRKENMAIER.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 6, first column. line 49. claim 29, for "floor" read door; and that the said Letters Patent should be read with this correction therein that the some may conform to the record of the case `in the Patent Office.

Signed and sealed this 29th day of June, A. D. 1937.

Henry Van Arsdale (Seal) Acting Commissioner of Patents 

